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            <h2 class="title" style="clear: both"><a id="heartbeats"></a>Managing Heartbeats</h2>
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      <p>
                    If your replicated application experiences few updates,
                    it is possible for the replication group to lose a
                    master without noticing it. This is because normally a
                    replicated application only knows that a master has
                    gone missing when update activity causes messages to be
                    passed between the master and replicas.
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      <p>
                    To guard against this, you can configure a heartbeat.
                    The heartbeat must be configured for both the master
                    and each of the replicas.
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                    On the master, you configure the application to send a
                    heartbeat on a defined interval when it is otherwise
                    idle. Do this by using the
                    <span>
                            <code class="literal">DB_REP_HEARTBEAT_SEND</code> value
                            to the <code class="literal">which</code> parameter of the
                            <code class="methodname">DB_ENV-&gt;rep_set_timeout()</code>
                            
                            method.
                    </span>
                
                You must also provide the method a value representing the period between heartbeats in microseconds. Note that the heartbeat is sent only if the
                system is idle.
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      <p>
                    On the replica, you configure the application to listen
                    for a heartbeat. The time that you configure here is
                    the amount of time the replica will wait for some
                    message from the master (either the heartbeat or some
                    other message) before concluding that the connection is
                    lost. You do this using the 
                    <span>
                            <code class="literal">DB_REP_HEARTBEAT_MONITOR</code> value
                            to the <code class="literal">which</code> parameter of the 
                            <code class="methodname">DB_ENV-&gt;rep_set_timeout()</code>
                            
                            method and a timeout value in microseconds.
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                For best results, configure the heartbeat monitor for a
                longer time interval than the heartbeat send interval.
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